Remove unnecessary dependency, and fix the chain

Test: No new tests. This should not affect behavior; only dependencies.

Font.h does not need to include SkGlyphCache.h, and doing so requires
a transitive dependency on external/skia/src/utils, which was not
intended. Forward declare it instead, and fix the build errors that
resulted.

Change-Id: Ifd09430bb848d51b139df0f0c06c63e7e48711eb
diff --git a/libs/hwui/font/Font.h b/libs/hwui/font/Font.h
index 288f733..504dabb 100644
--- a/libs/hwui/font/Font.h
+++ b/libs/hwui/font/Font.h
@@ -22,14 +22,16 @@
 #include <utils/KeyedVector.h>
 
 #include <SkScalar.h>
-#include <SkGlyphCache.h>
 #include <SkPaint.h>
 #include <SkPathMeasure.h>
+#include <SkTypeface.h>
 
 #include "FontUtil.h"
 #include "../Rect.h"
 #include "../Matrix.h"
 
+class SkGlyphCache;
+
 namespace android {
 namespace uirenderer {